A mechanically commutated motor has a wound rotor and a commutator which provides power to the rotor winding by brushes which make sliding electrical contact with the commutator. Heat is generated within the motor by the electric current flowing through the windings, through magnetic eddy currents in the steel of the rotor core, by friction between the brushes and the commutator, electrical erosion or sparking between the commutator and the brushes and by direct heating of the brushes by the current passing through each brush. This heat needs to be dissipated or removed from the motor or risk serious damage to the motor. Usually, a fan removes this heat by inducing a flow of air drawn into the motor housing and across the commutator or across the rotor core and windings. However, the brushes are not specifically cooled and under heavy load conditions the brushes may heat up sufficiently to reduce the working life of the brushes. This is especially a problem for guided brushes, such as those used with brush cages and even for rail guided brushes as the cage and/or end cap or brush card to which the brush guiding system is fitted restricts air flow about the brush, even in a relatively open brush gear arrangement.
As such, there is a desired for an improved electric motor which can solve the above-mentioned problem or at least provide a useful alternative.